/*
  Copyright 2014 Google Inc.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
*/

#include <windows.h>
#include <mmsystem.h>
#include <process.h>

#include "base/threading/platform_thread.h"
#include "base/time.h"
#include "base/at_exit.h"
#include "base/logging.h"
#include "testing/base/public/gunit.h"

using base::Time;
using base::TimeDelta;
using base::TimeTicks;

namespace {
base::AtExitManager manager;

class MockTimeTicks : public TimeTicks {
 public:
  static DWORD Ticker() {
    return static_cast<int>(InterlockedIncrement(&ticker_));
  }

  static void InstallTicker() {
    old_tick_function_ = SetMockTickFunction(&Ticker);
    ticker_ = -5;
  }

  static void UninstallTicker() {
    SetMockTickFunction(old_tick_function_);
  }

 private:
  static volatile LONG ticker_;
  static TickFunctionType old_tick_function_;
};

volatile LONG MockTimeTicks::ticker_;
MockTimeTicks::TickFunctionType MockTimeTicks::old_tick_function_;

HANDLE g_rollover_test_start;

unsigned __stdcall RolloverTestThreadMain(void* param) {
  int64 counter = reinterpret_cast<int64>(param);
  DWORD rv = WaitForSingleObject(g_rollover_test_start, INFINITE);
  EXPECT_EQ(rv, WAIT_OBJECT_0);

  TimeTicks last = TimeTicks::Now();
  for (int index = 0; index < counter; index++) {
    TimeTicks now = TimeTicks::Now();
    int64 milliseconds = (now - last).InMilliseconds();
    // This is a tight loop; we could have looped faster than our
    // measurements, so the time might be 0 millis.
    EXPECT_GE(milliseconds, 0);
    EXPECT_LT(milliseconds, 250);
    last = now;
  }
  return 0;
}

}  // namespace

TEST(TimeTicks, WinRollover) {
  // The internal counter rolls over at ~49days.  We'll use a mock
  // timer to test this case.
  // Basic test algorithm:
  //   1) Set clock to rollover - N
  //   2) Create N threads
  //   3) Start the threads
  //   4) Each thread loops through TimeTicks() N times
  //   5) Each thread verifies integrity of result.

  const int kThreads = 8;
  // Use int64 so we can cast into a void* without a compiler warning.
  const int64 kChecks = 10;

  // It takes a lot of iterations to reproduce the bug!
  // (See bug 1081395)
  for (int loop = 0; loop < 4096; loop++) {
    // Setup
    MockTimeTicks::InstallTicker();
    g_rollover_test_start = CreateEvent(0, TRUE, FALSE, 0);
    HANDLE threads[kThreads];

    for (int index = 0; index < kThreads; index++) {
      void* argument = reinterpret_cast<void*>(kChecks);
      unsigned thread_id;
      threads[index] = reinterpret_cast<HANDLE>(
        _beginthreadex(NULL, 0, RolloverTestThreadMain, argument, 0,
          &thread_id));
      EXPECT_NE((HANDLE)NULL, threads[index]);
    }

    // Start!
    SetEvent(g_rollover_test_start);

    // Wait for threads to finish
    for (int index = 0; index < kThreads; index++) {
      DWORD rv = WaitForSingleObject(threads[index], INFINITE);
      EXPECT_EQ(rv, WAIT_OBJECT_0);
    }

    CloseHandle(g_rollover_test_start);

    // Teardown
    MockTimeTicks::UninstallTicker();
  }
}

TEST(TimeTicks, SubMillisecondTimers) {
  // HighResNow doesn't work on some systems.  Since the product still works
  // even if it doesn't work, it makes this entire test questionable.
  if (!TimeTicks::IsHighResClockWorking())
    return;

  const int kRetries = 1000;
  bool saw_submillisecond_timer = false;

  // Run kRetries attempts to see a sub-millisecond timer.
  for (int index = 0; index < 1000; index++) {
    TimeTicks last_time = TimeTicks::HighResNow();
    TimeDelta delta;
    // Spin until the clock has detected a change.
    do {
      delta = TimeTicks::HighResNow() - last_time;
    } while (delta.InMicroseconds() == 0);
    if (delta.InMicroseconds() < 1000) {
      saw_submillisecond_timer = true;
      break;
    }
  }
  EXPECT_TRUE(saw_submillisecond_timer);
}

TEST(TimeTicks, TimeGetTimeCaps) {
  // Test some basic assumptions that we expect about how timeGetDevCaps works.

  TIMECAPS caps;
  MMRESULT status = timeGetDevCaps(&caps, sizeof(caps));
  EXPECT_EQ(TIMERR_NOERROR, status);
  if (status != TIMERR_NOERROR) {
    printf("Could not get timeGetDevCaps\n");
    return;
  }

  EXPECT_GE(static_cast<int>(caps.wPeriodMin), 1);
  EXPECT_GT(static_cast<int>(caps.wPeriodMax), 1);
  EXPECT_GE(static_cast<int>(caps.wPeriodMin), 1);
  EXPECT_GT(static_cast<int>(caps.wPeriodMax), 1);
  printf("timeGetTime range is %d to %dms\n", caps.wPeriodMin,
    caps.wPeriodMax);
}

TEST(TimeTicks, QueryPerformanceFrequency) {
  // Test some basic assumptions that we expect about QPC.

  LARGE_INTEGER frequency;
  BOOL rv = QueryPerformanceFrequency(&frequency);
  EXPECT_EQ(TRUE, rv);
  EXPECT_GT(frequency.QuadPart, 1000000);  // Expect at least 1MHz
  printf("QueryPerformanceFrequency is %5.2fMHz\n",
    frequency.QuadPart / 1000000.0);
}

TEST(TimeTicks, TimerPerformance) {
  // Verify that various timer mechanisms can always complete quickly.
  // Note:  This is a somewhat arbitrary test.
  const int kLoops = 10000;
  // Due to the fact that these run on bbots, which are horribly slow,
  // we can't really make any guarantees about minimum runtime.
  // Really, we want these to finish in ~10ms, and that is generous.
  const int kMaxTime = 35;  // Maximum acceptible milliseconds for test.

  typedef TimeTicks (*TestFunc)();
  struct TestCase {
    TestFunc func;
    char *description;
  };
  // Cheating a bit here:  assumes sizeof(TimeTicks) == sizeof(Time)
  // in order to create a single test case list.
  COMPILE_ASSERT(sizeof(TimeTicks) == sizeof(Time),
                 test_only_works_with_same_sizes);
  TestCase cases[] = {
    { reinterpret_cast<TestFunc>(Time::Now), "Time::Now" },
    { TimeTicks::Now, "TimeTicks::Now" },
    { TimeTicks::HighResNow, "TimeTicks::HighResNow" },
    { NULL, "" }
  };

  int test_case = 0;
  while (cases[test_case].func) {
    TimeTicks start = TimeTicks::HighResNow();
    for (int index = 0; index < kLoops; index++)
      cases[test_case].func();
    TimeTicks stop = TimeTicks::HighResNow();
    // Turning off the check for acceptible delays.  Without this check,
    // the test really doesn't do much other than measure.  But the
    // measurements are still useful for testing timers on various platforms.
    // The reason to remove the check is because the tests run on many
    // buildbots, some of which are VMs.  These machines can run horribly
    // slow, and there is really no value for checking against a max timer.
    // EXPECT_LT((stop - start).InMilliseconds(), kMaxTime);
    printf("%s: %1.2fus per call\n", cases[test_case].description,
      (stop - start).InMillisecondsF() * 1000 / kLoops);
    test_case++;
  }
}

// NOTE(henryou): The test is disabled because it fails on pulse continuous
// build. The QPC timer is not accurate on virtual machines and generate large
// drift to exceed the our limitation. We need to find some workaround when
// running on virtual machines.
#if 0
TEST(TimeTicks, Drift) {
  const int kIterations = 100;
  int64 total_drift = 0;

  for (int i = 0; i < kIterations; ++i) {
    int64 drift_microseconds = TimeTicks::GetQPCDriftMicroseconds();

    // Make sure the drift never exceeds our limit.
    EXPECT_LT(drift_microseconds, 50000);

    // Sleep for a few milliseconds (note that it means 1000 microseconds).
    // If we check the drift too frequently, it's going to increase
    // monotonically, making our measurement less realistic.
    base::PlatformThread::Sleep((i % 2 == 0) ? 1 : 2);

    total_drift += drift_microseconds;
  }

  // Sanity check. We expect some time drift to occur, especially across
  // the number of iterations we do. However, if the QPC is disabled, this
  // is not measuring anything (drift is zero in that case).
  EXPECT_LT(0, total_drift);

  printf("average time drift in microseconds: %lld\n",
         total_drift / kIterations);
}
#endif
